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Future Venus Missions
JRehling
post Oct 16 2020, 08:01 PM
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One also needs to know if "high" and "relatively high" are referring to the same altitudes or if there's some important difference there. I would guess that anything above the clouds, encountering direct solar UV, qualifies equally well as "high" for these purposes, but I never received a paycheck for studying Venus.
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rlorenz
post Oct 17 2020, 03:10 AM
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QUOTE (Xerxes @ Oct 16 2020, 12:34 PM) *
I suppose one would need a great deal more expertise to know whose argument is stronger.


Expertise, maybe. But as humans, we can also employ our heuristic tools of caricature, profiling and prejudice.

Therese Encrenaz has been in *planetary* spectroscopy a long time. I think (and my Planetary Climate book gives many examples) in planetary science there are many instances of spectroscopic detections being disproved by in-situ or other data, which make some people (like her) cautious. In stellar astronomy (which seems to be where the Cardiff group has more pedigree), I could imagine there are fewer disproved 'discoveries' just because there are fewer ways to confirm or refute initial announcements.

So, IMHO, if Therese says it isnt in her data, then it isnt in her data... (and knowing her, she wouldnt say it wasnt there on Venus, only that there wasnt evidence for it in her data).

It may be non-PC to consider such meta-factors, but at the hairy edge of detectability, one is obliged - Bayeswise - to weigh all the information.

There are sadly a lot of incentives in the journals and the media to talking up anything that could bear on life in the universe - indeed Nature Astronomy even had an editorial congratulating itself on how much press the paper had generated and how this was only possible because of their media embargo policy. Cui bono....

All this said, Venus deserved the attention.


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Greenish
post Oct 27 2020, 11:35 PM
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For what it's worth, this is new on the arxiv, not yet refereed:
Re-analysis of the 267-GHz ALMA observations of Venus: No statistically significant detection of phosphine
I.A.G. Snellen, L. Guzman-Ramirez, M.R. Hogerheijde, A.P.S. Hygate, F.F.S. van der Tak
https://arxiv.org/abs/2010.09761

"...The reported 15σ detection of PH3 1−0 is caused by a high-order polynomial fit that suppress the noise features in the surrounding spectrum. ...Low-order spectral baseline fitting shows a feature near the expected wavelength at a signal to-noise of only ∼ 2."

It does come with a front page caveat that there has since been an update to the ALMA processing pipeline [while this re-analysis was in work], that they haven't fully analyzed. It notes that though many of the "spurious ripples" are gone, they still see no clear PH3 feature.
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antipode
post Nov 23 2020, 03:24 AM
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Here's a Venus mission concept I hadn't seen before (apologies if its been covered further back).

https://www.hou.usra.edu/meetings/vexag2020/pdf/8045.pdf

Its a fascinating idea with potential high return, but I worry about that long cable and any shear/turbulence in between the baloon and the descent module.

P
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vjkane
post Nov 23 2020, 02:29 PM
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QUOTE (antipode @ Nov 22 2020, 07:24 PM) *
Here's a Venus mission concept I hadn't seen before (apologies if its been covered further back).

https://www.hou.usra.edu/meetings/vexag2020/pdf/8045.pdf

Its a fascinating idea with potential high return, but I worry about that long cable and any shear/turbulence in between the baloon and the descent module.

P


Fixed URL link


This abstract discusses a similar idea:

VENUS CORONA AND TESSERA EXPLORER Investigating the Surface of Venus from Beneath the Clouds [#8031]
VeCaTEx would use an aerobot to descend repeatedly beneath the dense clouds for imaging targeted area of the surface in the near infrared spectral region to address six of the prime investigations prioritized by VEXAG.[color="#FF0000"][/color]


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vjkane
post Nov 23 2020, 09:27 PM
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Moderators: I obviously had problems editing my previous reply and don't see a post delete button (sure I'm just missing the obvious). Please delete duplicates.

This is the correct link for the other poster at the recent VEXAG meeting for a mission concept that would go beneath the clouds for a more detailed examination of the surface.

Venus Corona and Tessera Explorer (VeCaTEx) Mission ConceptVisit My Website: Investigating the Surface of Venus from Beneath the Clouds [#8031]
VeCaTEx would use an aerobot to descend repeatedly beneath the dense clouds for imaging targeted area of the surface in the near infrared spectral region to address six of the prime investigations prioritized by VEXAG.


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JRehling
post Nov 23 2020, 10:07 PM
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As a non-mechanical engineer, I nonetheless share antipode's sense that a cable more than 20 km long seems to introduce some serious worries about practicality. I can't even picture something like that working on Earth, much less being transported to Venus.

Here's an informative analysis of aerobot architectures. I'd never heard of nor thought of some of these architectures.

https://dartslab.jpl.nasa.gov/References/pd...TitanVeinus.pdf

We are, apparently, about three months away from finding out whether Venus will prevail in the upcoming Discovery mission selection, and the ESA decision on Envision was said, in 2018, to be expected "in 2021." So the next few months will have profound impact on the course of Venus exploration, with anywhere from zero to three missions in the balance depending on those decisions.
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mcaplinger
post Nov 23 2020, 10:45 PM
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QUOTE (JRehling @ Nov 23 2020, 02:07 PM) *
As a non-mechanical engineer, I nonetheless share antipode's sense that a cable more than 20 km long seems to introduce some serious worries about practicality.

To put it mildly. At any rate, most of the concepts are just for a balloon that can change altitude by various means (see https://www.lpi.usra.edu/vexag/reports/Venu...ssion_FINAL.pdf sections 3.2.3 and B.2.8.1 for one such concept).


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Disclaimer: This post is based on public information only. Any opinions are my own.
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Gerald
post Yesterday, 02:21 AM
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I was wondering whether any fiber is known to be strong and heat-resistant enough, and found aramids, e.g. M5, possible candidates. I'm just not sure whether thin fibers would also be sufficiently weathering resistant under the harsh environmental conditions in the Venus atmosphere.
This is before thinking about the dynamics of such a tether in a dense and stormy atmosphere.
In space in Earth orbit, at least, some tether experiments were already performed in the 1990s (SEDS-1 and SEDS-2).
(More space tether missions.)
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mcaplinger
post Yesterday, 04:15 AM
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QUOTE (Gerald @ Nov 23 2020, 06:21 PM) *
In space in Earth orbit, at least...

I've talked with people who worked on TSS-1 and -1R and they had quite a few stories about it. Let's just say that I don't think tether technology is quite ready for a Venus mission.


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